README needs to be updated (SSH keys should no longer be made in PEM format)

[joseph-predibase]

Thank you for this wonderful tool, I spent waaaaay too long figuring out how to clone private submodules from github on my own...

One thing I had to do differently than the instructions in the README: The instructions say If the private key is not in the PEM format, you will see an Error loading key "(stdin)": invalid format message.. I actually could not get it work if the comment was in PEM format - the private key did not contain the required comment - and only got the plugin to work by encoding it in non-PEM format (i.e. by invoking ssh-keygen -t rsa -b 2048 -C <repo_path>.

A (small) comment here reads Nit: the privatekey file contains the comment only using 'new' format, which is the default for all types in 7.8 up, and in 6.5 to 7.7 only for ed25519. If you create(d) a non-ed key below 7.8, or in 7.8 up use -m pem (for non-ed), it does not.. This suggests that as of OpenSSH 7.8 (for non ed25519 keys) if you use PEM format the private key does not include the comment (and your plugin does not work), and non-PEM format is required. Thankfully this fixed my issue.

Again thank you very much for this action, it was a lifesaver.